The U.S. Postal Service says its downtown post office is too big and it wants to move into smaller quarters, according to Mayor Susan Haynie. The office at 170 NE Second St. is about 8,000 square feet; Haynie said postal officials told her they want a 4,000-square-foot facility. The first step in relocating the post office is a public meeting, scheduled for 4:30 p.m. March 29. A USPS real estate specialist based in Dallas, Texas, will…